Process of drilling holes.



G. H.`G|LMAN. r PROCESSe 0F DBIILLINGKHOLES.

APPLICATION FILED ocT. s. Isls.A

Patented Jan. 7, 1919.

' rotary drill which was subsequently modif GEORGE H. GILMAN, or CLAREMONT, NEW HAMPSHIRE, AssIGNoR To SULLIVAN MACHINERY COMPANY, OE BOSTON, MASSACHUSETTS, A CORPORATION or MASSACHUSETTS.

My invention relates to processes of drill ing holes in minerals, andmore particularly though not exclusively to processes of drilling holes in rock. A

There have come into general use three great generic classes of drills for drilling rock.l Of these the oldest is probably the fied into the core drill.k -The core drill uses a drill bit having a relativel large hole, the bit being pressed against t e rock and rO- tated, therebyv cutting an annular channel in the rock about a core protected by the sur- A solid drill steel or one having a relatively rounding bit. The .cutting by rotary action alone is relatively slow, and this method of drilling holes is'rarely used in connection with power-drills 'except where it is desired to preserve the core.

The second great method 'of drilling holes in extensive use, is the reciprocatory drilling system, which is essentially percusslve.

small hole for the introduction of cleansing fluid is used, which steel is reciprocated to strike a series of percussive blows on the rock to be drilled, usually with rotation of' the steel betweenbut not during the blows. A modification :f this system uses a drill bit having a large hole therein so that an annularv channel is out. This is done, not to save the core, but to drill a hole of relatively J large diameter while -abrading a relatively small amount of rock. Several disadvantages accompany this method. The drill, relying on impact owingto its momentum does not cut as fast when lightened, andthe withdrawal of the drill steelfrom the end of the hole between the blows permits'pieces y of the, core (which generally is somewhat shattered) to fall in front of the bit and prevent the securing of the maximum eiiiency thereof for subsequent cutting. l

Sieeicatto oflLetters Patent.

Application fuea october s; 1915. serial No. 54,252.

rRoCEss OF DRILLING HOLES.

,ratentedaan'- t, raie.'

The third method of drilling, commonly called the hammer drill method, uses a bit f-,either solid or with a relatively small hole therein, which is held loosely in the path of a reciprocating power hammer element, ro'

tation usually being given to the drill steel between successive blowsof the hammer ele` ment. 'This method, while very successful,

has several disadvantages. Practically all tain depth is (passed, `absorbs much of the" blow imparte by the hammer. lAn improvement which has recently come into eX- tensive use comprises the use of a pressure fluid' feed' 'to press the drill against the work; but', 4although this greatly increases Ythe efiiciency of the drill by eliminating, to

some extent, the personal equation, hammer `I so desire. I am enabled-to drill holes of much larger diameter in proportion to the size of drilling engine used, also saving a Core, if so desired. I can also largely overcome the-usual disadvantages attending the drills are used generally only `forrdrilling A drilling of holes of relatively great depth,

by to a large extent reducing the linertia. or

1 anvil efect of the drill andv alsothe side spring thereof.

I may accomplish the above by a process of drillin holes which comprises cutting an annular c annel aroundv a coreof rock by combined -percussive and rotary action of al` 4non-reclprocatory core surrounding element,

and removingthe core, thereby cutting a 4relatively large hole by abrading a relatively small amount of rock. The bit, having a relatively large hole axially therein, is relatively Alight in proportion to its diameter;

thus whatis a disadvantage a reciprocatory core drill becomes an advantage in the p' hammer core drill, for in the former the reciprocatory steel should have weight to increase the impact, whlle in the latter weight should be avoided to increase the impact.

It is also well understood that a tube the strongest structure into which a given amount of metal can be formed to withstand bending strain or side spring in all directions. Thus in proportion to the cross sec-4 tional area of my drill bit, and hence in proportion to the amount of stone to be abraded, my process provides a means of avoiding, to a large extent, the absorption of the impact by side sprin of the steel.

I preferab y press my drill steel toward the work by a constant pressure during the drilling operation. Thus the steel is firmly pressed against the work so that there is substantially no rebound thereof following the blows thereon, and also the pressure is availalble during the rotary action of the drill bit to abrade somewhat the material being cut, even between the blows of the hammer drilling engine.

It will be noted that yby my process the core may be constantly surrounded and supported throughout. its entire length by the drill steel. Thus even if the core becomes cracked, as is usually the case, it will remain in its 4proper position within the drill steel.

My process is adapted to be used in drill- -ing holes in any direction, but is peculiarly well adapted for drilling holes horizontally at an upward angle to the horizontal or at a slightly downward angle to the horizontal, for in drilling holes in these directions practically the whole. core usually comes out within the drill bit, for seams in the rock or the shaking 4of the |bit usually cause a crack across the core adjacent the end of the bit.

To prevent friction and, if desired, to introduce water or air and water to wash away the material ab-raded, I may construct my hollow cutting member with a slightly restricted opening adjacent the cutting edges, so that the core, except at and adjacent the cutting point of the bit, is loosely held in the hollow of the drill steel so that it may crack into sections, and so that, if desired, the water or air or a mixture of the two may pass around the core to the point of the bit and cause the abraded material to leave the vhole by passing Iback alone' the exterior of the drill steel, which is preferably somewhat enlarged in diameter at the cutting point.`

form my process when properly handled by a skilled operator. v

In the drawings' of this illustra-tive appa-- atus z-Figure 1 is a sectional view, partly in elevation, of a Ipressure fluid fed, rotative hammer drilling engine having connections for 1feeding air or water or both to the drill Stee Fig. 2 is an enlarged side elevation, partly in section, of the point of abit adapted to be used in connection with my process.

Fig. 3 is an enlarged end elevation of the point of the drill bit illustrated in Fig. 2.

Fig. 4 is ay sectional elevation on the line 4 of Fig; 3.

As the construction and operation of drilling engines is well known tothose skilled in the art, and as my present invention pertainsl to processes of drilling and not to det-ails ,of

construction other than the generic types of.

construction referred to in describing my process, I make no detailed description of the apparatus illustrated.

While I have descri'bed rather specificallyl the process of drilling, and have illustrated al drilling apparatus well adapted to perform my process, I do not limit myself to the proc'- ess described. ,The scope 4of my invention nular channel around a core by alternate percussive and rotary abrasive action of a cutting element produ-ced Iby alternately percussing and rotating said element, said element being held aainst the rock during Iits rotation with a sufiicient pressure to exert an abrasive action on said rock.

2. ,That process of drilling relatively large holesin rock which comprises cutting an annular channel around a core by alternately percussing and rotating a cutting element while holding said element in engagement with the rock and preserving said core substant-ially intact. y

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing Witnessesc GEORGE I-I. GILMAN.

Witnesses:

W. ALEX. Rien, MARY A. GAFFNEY. 

